Compound filament of two polymers with different shrinkage capacities

ABSTRACT

N BEING 2,3 OR 4 AND THE MOL PERCENT BEING TAKEN WITH REFERENCE TO THE MOLS OF ADIPIC ACID.   H2N-(CH2)3-0-(CH2A-0-(CH2)3-NH2   AN IMPROVED COMPOUND FILAMENT HAVING AN ACCENTRIC CORE AND MANTLE STRUCTURE IN WHICH THE MANTLE IS A HOMOPOLYAMIDE SUCH AS POLYHEXAMETHYLENE ADIPAMIDE OR POLYCAPROLACTAM, AND THE CORE IS A COPOLYETHERAMIDE OF (A) ADIPIC ACID WITH (B) 25-80 MOL PRECNET OF HEXAMETHYLENE DIAMINE AND 75-20 MOL PRECENT OF AN ETHERDIAMINE OF THE FORMULA H2N-(CH2)3-NH2 OR

1971 E. SOMMER ETAL 3,55

COMPOUND FILAMENT OF TWO POLYMERS WITH DIFFERENT SHRINKAGE CAPACITIES Filed May 17, 1968 CRIMP EXTENSION f/a r l l 4O 5O 6O 7O 8O SHRINKAGE CAPACITY 7,

l 1' z-' 7 1 20 50 m0 200 400 800 I600 3200 e400 l2800 LOAD INVENTORSI ERWIN SOMMER FRITZ WILOTH HELMUT WERNER RUDOL'F LOTZ GERHARD WICK ATT'YS United States Patent U.S. Cl. 161-173 Claims ABSTRACT OF THE DISCLOSURE An improved compound filament having an eccentric core and mantle structure in which the mantle is a homopolyamide such as polyhexamethylene adipamide or polycaprolactam, and the core is a copolyetheramide of (A) adipic acid with (B) 2580 mol percent of hexamethylene diamine and 75-20 mol percent of an etherdiamine of the formula H N-(CH O(CH NH or n being 2, 3 or 4 and the mol percent being taken with reference to the mols of adipic acid.

It has become of increasing importance in the textile industry to obtain so-called producer textured yarns of synthetic thermoplastic filaments or threads, i.e. where the texture is imparted to the yarn or filaments during the initial production and processing of the thermoplastic polymer into filaments, fibers, threads or the like. Many texturizing processes are known in the art, various mechanical techniques being most widely followed as a means of altering the physical structure of the normally straight, smooth and non-textured thermoplastic filaments. Thus, it is a conventional practice to impart a mechanical crimping to the filaments so as to produce regular or ir regular arcs, bends or the like in the length of each filament. Such crimping can also be produced, according to more recent developments, by using so-called compound filaments where each filament consists of two polymer components, each of which has a different shrinkage characteristic.

For purposes of the present invention, the term compound filaments is restricted to its technical definition of monoor multi-filament threads which are produced in a known manner by spinning two different polymer components through specially designed nozzles. These nozzles are equipped with certain devices which permit two different polymer spinning solutions or two different polymer spinning melts to be spun or extruded from the nozzle opening in such a manner as to cause the formation of core-mantle filaments, i.e. wherein one polymer forms the core or inner cross-section of the filament and the other polymer forms the mantle or outer cross-section as in a jacket or sheath around the core.

It is preferable to spin or extrude the two polymer components so as to provide an eccentric formation of the core and mantle, i.e. such that they are formed crosssectionally around different centers, and each of the two polymers may partly form the filament surface while also partly forming the center or interior of the filament. It

is this eccentric structure of the bicomponent filament together with the difference in shrinkage capacity of the two polymers which permits the produced filament to be crimped in a desirable manner.

Thus, an especially important significance is attached to those compound filaments which, immediately after Patented Jan. 19, 1971 spinning and stretching, can be caused to form crimping either without any special treatment or by a simple treatment with water, steam or the like. For the production of such compound filaments, it is essential to use polymers having distinctly different physical and/ or chemical properties, particularly those having a strongly different capacity for shrinkage. A crimping will then always occur if both polymers form at least part of the outer or peripheral surface of the filament or if there is at least a clearly defined eccentric formation of the core-mantle structure.

In a known process relating to the production of compound filaments from two polymers, each exhibiting a different capacity for shrinkage, it is recommended that the more strongly shrinking filament component should have a shrinkage capacity of at least 7% and that the difference in shrinkage capacity as between both components should amount to at least 10%, preferably 20%. As examples of useful polymer combinations for the bicomponent filament, there has been suggested nylon (polyhexamethylene adipamide or polycaprolactam) as one component while using a polyester such as polyethylene terephthalate as the other component. In addition to these polymers, however, one of the filament components can also be a copolyamide or a copolyester.

Compound filaments, which have been produced according to known processes with the use of various different polymer combinations, exhibit a more or less strong crimping effect after being subjected to a heat treatment. The amount of crimping depends in part on the type of polymers combined and their composition and shrinkage properties. By way of example, a compound filament having an eccentric core-mantle structure and consisting of a polyamide and polyethylene terephthalate as the two polymers has been found to exhibit a crimping are number of 115 per 10 cm. after a treatment with water at C. However, it would be desirable to obtain a compound filament having a substantially higher crimping arc numher as well as other beneficial properties.

One object of the present invention is to provide a compound filament having an eccentric core and mantle structure and possessing novel and superior properties, especially with regard to its crimping are number. Another object of the invention is to provide a compound filament in which the two component polymers are more compatible and in which at least one component exhibits high shrinkage values at relatively low temperatures. Other objects and advantages of the invention will become more apparent upon consideration of the following detailed disclosure.

In accordance with the invention, it has now been found that an improved melt-spun compound filament exhibiting an eccentric core and mantle structure can be achieved if it includes: (1) a mantle consistin of a homopolyamide, i.e. a typical fiber-forming polyamide having essentially only the recurring group NHCO- in an otherwise hydrocarbon structure, e.g. polyhexamethylene adipamide or polycaprolactam; and (2) a core consisting of a copolyetheramide obtained by the polycondensation of (A) adipic acid with (B) 25 to 80 mol percent, preferably about 50-60 mol percent, of hexamethylene diamine and 75 to 20 mol percent, preferably about 50-40 mol percent, of an etherdiamine of the formula wherein R denotes a member selected from the group consisting of O and O(CH -O with n being an integer of 2 to 4, said mol percent being taken with reference to the adipic acid. The sum of the molar percentages of the hexamethylene diamine and the etherdiamine should of course be approximately mol percent with reference to the mols of adipic acid. The proportion by weight of the mantle to the core should be maintained within a range of about 30:70 to 70:30, and the mantlezcore ratio is preferably about 50:50.

As the mantle component of the compound filament, one can suitably use any of the known linear fiber-forming homopolyamides characterized by the recurring unit NHCO in an otherwise essentially hydrocarbon structure, e.g. homopolymers of caprolactam or homopolymers of a number of dicarboxylic acid-diamine salts or their equivalent such as hexamethylene adipamide (the so-called AH-salt) or similar combinations of alkylene diamines NH (CH ),,NH and alkylene dicarboxylic acids HOOC(CH COOH, in which n is to 12, including cycloaliphatic diamines and dicarboxylic acids. Other suitable homopolyamides include the homopolymer of amino-'undecanoic acid and the like, i.e. amino-alkanoic acids of about 6 to 12 carbon atoms.

Especially preferred properties are exhibited by compound filaments in which the mantle consists of polyhexamethylene adipamide or polycaprolactam, both of which are readily available as conventional homopoly amides, and in which the core consists of the copolyetheramide obtained by the polycondensation of adipic acid with approximately 60 mol percent hexamethylene diamine and 40 mol percent of the etherdiamine of the formula The copolyethyleramides serving as the core component are produced in accordance with the Belgian patent specification No. 701,477 (corresponding with US. application Ser. No. 656,251 filed July 26, 1967). According to the process described therein, the copolyetheramides are successfully produced in any arbitrary ratio of etherdiamine:hexamethylenediamine with an about equimolar amount of adipic acid so as to achieve a copolymer of adequately high molecular weight and good fiber-forming properties. These copolyetheramides possess a surprisingly high capacity for shrinkage.

In Table I, data has been collected for the shrinkage values of a copolyetheramide with various proportions of the hexamethylene diamine and etherdiamine as compared to the values of other polyamides, as measured in Water at 95 C. and at 20 C.

TABLE I Fiber material This table shows that the copolyetheramide (1) which is prepared with 30 mol percent hexamethylene diamine and 70 mol percent of the etherdiamine and which exhibits the least amount of shrinkage in water at 95 C., still has a shrinkage Which lies at the order of magnitude of the copolyamide (4). This same high shrinkage occurs with the copolyetherami-de of 50 mol percent each of hexamethylene diamine and the etherdiamine even when treated in water at only 20 C. Due to the large shrinkage capacity of the copolyetheramide, it is possible to use this copolymer as one component in the core-mantle structure of a compound filament so as to achieve a correspondingly high crimping etlect.

The compound filaments according to the present invention are produced by the well-known melt-spinning process which is carried out at the usual temperatures for the melt-spinning of the homopolyamide employed as the mantle component. Conventional process conditions are employed throughout the fiber-forming procedure, and no changes or deviations are required either in the meltspinning process or in the stretching procedure.

The production of the compound filaments of the invention is further explained in the following example:

By means of a conventional spinning nozzle equipped to produce core-mantle filaments having an eccentric structure with reference to the respective centers of the core and mantle, the melt of a homopolyamide was spun as the mantle and the copolyetheramide Was spun as the core. Both polycaprolactam and polyhexamethylene adipamide were used as the homopolyamide while the copolyetheramide was that obtained by the polycondensation of adipic acid, hexamethylene diamine and the etherdiamine of the formula in various proportions of the two diamine ingredients. The temperature of the spinning device amounted to 280 C. The spun filaments were drawn oif at a linear velocity of 750 meters/minute from the nozzle, then 40 stretched cold in a ratio of 1:35 and finally taken up on a spool or bobbin. In Table II, below, textile data is given for the compound filaments of the invention when using different compositions of the copolyetheramide as well as different proportions by weight in the core as com- 45 pared to the mantle. For purposes of comparison, data is also given for known compound filaments.

For the measurement of those properties of the compound filaments which are not known per se, the following methods were used, according to which the crimping 50 was first relieved by a two-minute period of treatment with water at 95 C. in all cases.

(1) CRIMP EXTENSION A fiber sample of about one meter in length, which 55 had been treated in this manner, was first weighted with a load of 50 rug/denier, to the extent that the crimping was completely pulled out or extended. The extended fiber was fastened to the upper rim of a slightly inclined TABLE II Shrinkage Compound filament Percent Titer, in water,

by wt., denier, Elongapercent mCriping Crimp ex- Crimp Mantle, Core, copulymantle: individual tion, Strength, are number tension, contraction, polyamide etheramide core filaments percent g. [denier 95% 20% per 10 cm. percent percent 1 Not determined. 2 Copolyarnide. 3 Polyethyleneterephthalate. Norm-(i) Polycaprolactam.

(2) Polyhexamethylene adipamidc.

(3 Copolyamide of caprolactam and adipic acid-hexamethylenedlamina in molar ratio 80:20.

Copolyethera-mide of adipic acid with hexamethylene diamine and etherdiamine in molar ratio 60:40.

(b) Copolyetheramide of adipic acid with hexamethylene diamine and etherdiamine in molar ratio 30:70. (0) Copolyetheramids of adipic acid with hexamethylene diamine and etherdiamine in molar ratio 80:20.

wall. There was then clamped directly over the weight a smaller weight of 0.5 mg./denier and this was followed by a careful removal of the larger weight. Under this load, the fiber was left for twelve hours under normal atmospheric conditions. After this time, the fiber was fastened with the weight attached thereto in an electronic tensile strength testing machine and the extension was determined with a load of 0.05 gram/denier.

(2) CRIMP CONTRACTION A small fiber strand (8 meters long) was wound and hung for 30 seconds free of tension in 70 C. warm distilled water. The wet strand was loaded in the water for one minute with a weight of 0.2 gram/denier. The length of the strand maintained under this load was designated as x. After removal of the weight, the strand was dried while hanging free without a load for 30 minutes at 50-60 C. and thereafter climatized, i.e. brought to normal atmospheric conditions, for one hour. Then, the strand was loaded for one minute with a weight of 0.002 gram/denier. The length obtained in this manner was designated as y. The calculation of the crimp contraction was accomplished according to the equation Curve d or d =plycaprolactam (1) and copolyetheramide (a note Table II.

Curve e or e =polycaprolactam (1) and copolyamide (3), i.e. 80 mol percent caprolactam and mol percent hexamethylenediamine-adipic acid.

Curve or f =polycaprolactam and polyethyleneterephthalate.

In each case, the mantle consists of the first-named polymer while the core is the second-named polymer. The proportionate amounts or weight ratio of mantle:core are in all cases 50:50 and the filament titer is 40 denier (10 individual filaments).

For the determination of the crimp extension values for FIG. 1, the filaments were fixed on a frame with a clamping interval of cm. in each case and in such a manner that different shrinkage capacities were given. With a 10% shrinkage capacity, the clamped length of filament amounted for example to 33 cm., while at 80% shrinkage capacity, this length was 54 cm. The thus clamped filaments were next boiled for 60 minutes in water, then dried for 60 minutes in hot air (60 C.) and finally fixed for three minutes at 115 C. in saturated steam. The determination of the crimp extension was carried out, as described following Table II, with the difference that the length of the measured filament sample amounted to only 30 cm.

The crimp extension values as seen in FIG. 2 were determined by treating the filaments in water for two minutes at 95 C. under the various loads described by the diagram. From both diagrams, it will be apparent that the compound filaments according to the invention exhibit the most favorable crimping properties.

One special advantage of the compound filaments according to the invention resides in the fact that they have a capacity for shrinkage with a surprisingly high crimping even though they are merely immersed in water at room temperature. By comparison to known compound filaments in which the core may consist of polyethylene terephthalate and the mantle consists of a homopolyamide, the filaments produced in accordance with the invention also have the advantage that the core and mantle remain firmly connected with each other, primarily because of the much greater chemical or structural similarity of the two polymer components.

The invention is hereby claimed as follows:

1. In a compound filament of two different polymers exhibiting an eccentric core and mantle structure, the improvement which comprises: a mantle consisting of a homopolyamide and a core consisting of the copolyetheramide obtained by the polycondensation of (A) adipic acid with (B) 25 to 80 mol percent of hexamethylene diamine and 75 to 20% of an etherdiamine of the formula H N(CH -R.(CH NH wherein R denotes a member selected from the group consisting of O and O-(CH O with n being an integer of 2 to 4, said mol percent being taken with reference to the adipic acid.

2. A compound filament as claimed in claim 1 wherein the copolyetheramide is obtained by the polycondensation of (A) adipic acid with (B) about 50 to 60 mol percent of said hexamethylene diamine and about 50 to 40 mol percent of said etherdiamine.

3. A compound filament as claimed in claim 1 wherein the weight ratio of mantlezcore is about 30:70 to :30.

4. A compound filament as claimed in claim 1 wherein the mantle consists of polyhexamethylene adipamide and the core consists of the copolyetheramide of adipic acid with approximately 60 mol percent hexamethylene diamine and approximately 40 mol percent of the etherdiamine of the formula 5. A compound filament as claimed in claim 1 wherein the mantle consists of polycaprolactam and the core consists of the copolyetheramide of adipic acid with approximately 60 mol percent hexamethylene diamine and approximately 40 mol percent of the etherdiamine of the formula:

References Cited UNITED STATES PATENTS 3,397,107 8/1968 Kimura 16l173 ROBERT F. BURNETT, Primary Examiner L. M. CARLIN, Assistant Examiner US. Cl. X.R. 

